It's not Muay Thai, it's Muay Boran. Flying knee, elbow from the top of the head, and breaking bones intentionally like in this scene. That is not allowed in any martial art competition. The goal is always knockout or tap out without the cause of permanent injuries. So in the 1930's they wanted to make an accepted sport out of Muay Boran like Boxing and Karate was. Muay thai became the reformed version that we see in UFC today.
